Embodiments of the present invention relate to the filtration of fluids, such as liquids, vaporized liquids or gases, which are used in substrate processing apparatus.
In the processing of substrates used in electronic and solar applications, semiconducting, dielectric, and conductor layers are formed or deposited on a substrate, such as a semiconductor wafer or panel. The substrate and layers can be etched to form patterns of features such as gates, vias, contact holes and interconnects. Other materials can also be formed on such substrates using processes such as chemical vapor deposition (CVD), physical vapor deposition (PVD), implantation, oxidation and nitridation. For example, in CVD processes, a process gas is used to deposit a layer of material on the substrate. In PVD processes, a target is sputtered to deposit material on the substrate. In oxidation and nitridation processes, a layer of oxide or nitride, such as silicon dioxide or silicon nitride, is formed by exposing the substrate to a suitable gaseous environment. In etching processes, a patterned etch-resistant mask of photoresist or hard mask is formed on the substrate by photolithographic methods, and the exposed portions of the substrate are etched by an energized gas.
In some of these processes, the substrate is exposed to a process gas comprising a vaporized liquid, liquid vapor transported by a carrier gas, or a gas. As an example, vaporized liquid can be formed by evaporating a liquid precursor or bubbling a carrier gas through a liquid, and transporting the vaporized liquid to the process chamber. For example, a liquid precursor such as TriMethyl Silane (TMS), OctaMethyl-CycloTetraSiloxane (OMTCS) or methyl-Diethoxy-Silane (mDEOS) can be vaporized and used to deposit a low-K dielectric material on the substrate. Low-k dielectric materials have a low dielectric constant “k” that is typically less than about 3, such as for example, compositions of silicon, oxygen, carbon, and hydrogen, for example BLACK DIAMOND™ available from Applied Materials, Santa Clara, Calif. As another example, a liquid precursor comprising titanium tetrachloride (TiCl4) or tetrakisdimethyl-amidotitanium (TDMAT) can be used to deposit titanium-containing layers in a CVD process. As still another example, silicon oxide layers can be formed by evaporating a liquid precursor comprising tetraethylorthosilane (TEOS).
However, blockage and contamination problems often arise in the transportation and gas flow control of the liquid precursors themselves, the liquidized vapors, combinations of vapors and gases, or even just a gas by itself, to the process chamber. For example, in one process, a bubbler or boiler is used to transport vaporized liquid to the chamber by bubbling a carrier gas through a liquid precursor tank to form a stream of liquid vapor. However, the amount of vapor carried by the gas stream is difficult to control or measure because it depends on the downstream pressure, carrier gas flow rate, and the vapor pressure in the tank. Thus, complex multi-component delivery systems were developed to provide steady and continuous flow rates of vaporized liquid to a chamber, as for example, described in commonly assigned U.S. Pat. No. 6,783,118 to Sivaramakrishnan et al., filed on Jul. 31, 2001, and US Patent Application Publication No. 2003/0049933 A1 to Lei et al., filed on Mar. 13, 2003, both of which are incorporated by reference herein in their entireties. Such multi-component fluid delivery systems use vaporization valves, flow meters, and other control mechanisms to control the flow rate of the liquid or liquid vapor. However, many of these components have relatively narrow openings which can get clogged with residues of the liquid precursor or vapor causing variations in the vaporized liquid flow rates, until eventually the chamber is shut down for cleaning.
For reasons including these and other deficiencies, and despite the development of various vaporized liquid and fluid delivery systems, further improvements in such delivery systems and methods for supplying liquid precursors to substrate processing environments are continuously being sought.